Bill Seems to Be Connected to Every Marketing Project That

Bill seems to be connected to every marketing project that has had information leaked to the same competitor. Someone notices on a myspace page some photographs of Bill socializing with some executives of that competitor. Bill is sent on vacation for a week, and a supervisor access Bill's email and notices repeated emails with silly documents attached like jokes, random lists, or cooking recipe's.
He asks you if this seems suspicious and wonders if these are coded messages. You tell him it is even easier than that, and suspect which of the following techniques?

A) ADS Streams are being used to smuggle documents using a USB key
B) Steganography is being used to tunnel the secrets through the VPN
C) this host was compromised by foreign hackers and Bill is the real victim
D) snow.exe could be used to hide data inside the attached documents